Environmental regulations increasingly mandate liquid fuels containing very low levels of sulfur and nitrogen species. Hydrotreating is the most often used method for reducing sulfur and nitrogen content in a hydrocarbon feed. In general, harsher hydrotreating process conditions and advanced catalysts are required to further reduce sulfur from about 20 ppm to less than about 1 ppm, because of recalcitrant sulfur and nitrogen species to be reduced, including, for instance, 4,6-dimethyl dibenzothiophene, methyl, ethyl dibenzothiophene, trimethyl dibenzothiophene, carbazole and alkyl-substituted carbazole. The harsh hydrotreating conditions in turn result in further hydrocracking of diesel and jet fuel to C1-C4 gas and naphthene products, which may be undesired, as well as undesirable high hydrogen consumption.
It would be desirable to develop a process to reduce sulfur and nitrogen compounds in a hydrocarbon feed while avoiding the aforementioned problems. It is known that prior removal of nitrogen compounds from the hydrocarbon feed results in increasing the sulfur removal capacity, since both nitrogen and sulfur compounds target the same adsorption and/or hydrodesulfurization sites on the adsorbent or hydroprocessing catalyst and nitrogen being more polar is preferentially adsorbed.
Ionic liquids immobilized on a functionalized support have been used as catalysts, for example, in the hydroformulation reactions/Friedel-Crafts reactions.
There is a need for an improved process employing supported ionic liquids, in which sulfur and nitrogen compounds, such as carbazole and indole and their alkyl substitutes would be removed from hydrocarbon feeds.